Before replacing a Buick Century window regulator, always check to see if the window motor or the regulator is the problem. Turn the ignition key on and listen for the window motor. If the motor can be heard when you move the switch and the window does not move, the regulator is definitely bad. If the motor does not work then the motor is the problem. Depending on the model year, the motor comes with the regulator assembly. Check to make sure the other windows work to make sure the problem is isolated to that door. Check the switch to make sure the motor is getting power.
Remove the Phillips screws in the armrest and the screw in front of the door handle which leaves an access for the door panel to be removed with the door handle in place. Remove the plastic cover that conceals the mounting surface of the outside mirror. Use a screwdriver and pry it off gently as it just snaps on.
Insert the common screwdriver in between the door panel and door frame at the top side and slide it down until it contacts one of the snaps that holds the door panel and pry it out. There are usually three male plugs on each of the three sides of the door panel. Pry all the snap plugs out of their recess in the door.
Tip the bottom of the door panel out a little and lift up to unhook the top sill from the door channel. At the top of the door panel where it curves it hooks on to a channel running parallel with the panel next to the window. Disconnect all electrical connectors to the window switch and the marker light on bottom of door. Disconnect the wiring harness to the window motor.
Remove the two bolts at the bottom of the window holding the window to the regulator. Insert the common screwdriver downward (carefully, so as not to scratch the window) in between the window and door frame and use it as a wedge to hold the window up. Remove the nuts on the top and bottom of the window regulator vertical runners. Remove the bolts holding the window motor to the door. These are very obvious with the door panel off.
Remove the regulator through the access in the door. Install the new regulator through the access in the door and stand it up properly. Pull the studs in the upright vertical runners into their holes and install the nuts and tighten. Install the bolts in the window motor and plug the wiring harness connector into the window motor.
Hold the door panel close enough to the door and connect the window switch. Turn the key on and raise the window regulator to the middle of the access in the door where it will be easy to get to the window bolts. Remove the wiring connector from the window motor and remove the panel. Hold the window so it does not fall and remove the screwdriver being used as a wedge. Lower the window to the regulator horizontal channel in the door access. Line the holes at the bottom of the window up with the holes in the channel and insert the bolts and tighten. Install the door panel and screws in reverse order of removal.
